1. Field of Invention
The present invention relates to a method for removing oxygen from aluminum nitride by carbon and, more particularly, to a method for quenching an aluminum nitride substrate in an environment of carbon and nitrogen in an oven so that the carbon reduces oxygen contained in the oven and oxygen included in the aluminum nitride substrate into carbon monoxide or carbon dioxide, thus making a pure, quality aluminum nitride substrate.
2. Related Prior Art
LED devices have become popular recently because they operate at high efficiencies while consuming only a little electricity and are friendly to the environment.
Currently, most LED devices are used as backlights for cell phones. LED devices are however expected to replace conventional lights in the future. To this end, there is still a long way to go. There are problems related to the conversion efficiency, heat dissipation, color rendering, life and price for example.
Regarding the heat dissipation, an LED device converts a portion of electricity into light but converts the other portion of the electricity into heat. The heat would increase the temperature of the LED device excessively and therefore affect the efficiency, life and stability of the LED device should it not be dissipated fast.
Aluminum nitride (“AlN”) is suitable for use as a heat sink and a substrate of an LED device because it exhibits a high heat transfer coefficient (170 W/mK), a high insulation resistivity and an excellent mechanical strength and is refractory and vibration-resistant. The heat transfer coefficient of an aluminum nitride substrate is much higher than the heat transfer coefficient (20 W/mK) of a conventional substrate made of sapphire (“Al2O3”). Hence, aluminum nitride substrates are getting more and more attention in the field of high-power LED devices.
As the heat transfer coefficient of an aluminum nitride substrate is 7 times higher than the heat transfer coefficient of a sapphire substrate, the aluminum nitride substrate increase the life of an LED device to 6,0007,000 hours. The aluminum nitride could however be oxidized on the surface easily. That is, a thin layer of aluminum oxide could easily be formed on the surface of the aluminum nitride substrate. The thin layer of aluminum oxide compromises the quality and concentration of the aluminum nitride substrate and might even affect the heat dissipation.
The present invention is therefore intended to obviate or at least alleviate the problems encountered in prior art.